A Wind-Tunnel Study of Gliding Flight in the Pigeon Columba Livia

ABSTRACT A technique for training pigeons to fly in a tilting wind tunnel is described, and a method of determining lift and drag in gliding flight is explained. Drag measurements were made on wingless bodies and preserved feet in supplementary experiments. The results were used to analyse the measured total drag of live pigeons into (a) body drag, (b) foot drag, (c) induced drag, and (d) wing profile drag. As speed is increased, gliding pigeons drastically reduce their wing span, wing area and aspect ratio. The increased induced drag resulting from this is more than offset by a very large reduction in wing profile drag. Although the lift:drag ratio is at best 5·5-6·0, changes of wing area and shape keep it near its maximum, up to speeds at least twice the minimum gliding speed.